Combined variable resistance and switch



Sept# 9, 1941- E. R; sToEKLE 5 2,255,132

COMBINED VARIABLE RESISTANCE AND SWITCH Filed Dec. e, 1935 s shets-sheet 1 ATTORN EYS Sept. 9, 1941.- E. R. STOEKLE `COMBINED VARIABLE RESISTANCE AND SWITCH Filed Dec. 6, 1935 5 Sheets-Sheet 2 INVENTOR BY 6a-mud,

Sept. 9, 1941. E. R. sTor-:KLE 2,255,132

COMBINED VARIABLE RESISTANCE AND SWITCH Filed Dec. 6, 1955 s sheets-sheet s INVENTOR 77'] E. Mc/1,4,

ATTORNEY?)2 Patented Sept. 9, 1941 UNITED STATES PATENT oFFjlcE COMBINED VARIABLE RESISTANCE AND SWITCH Erwin B. Stoekle. Milwaukee, Wis., assigner, by

meme assignments, to Globe-Union Inc., Milwaukee, Wis., a corporation oi.' Delaware Application December 6, 1935, Serial No. 53,139 Claims. (Cl. 2151-48) This invention relates to a control device,

'such as a combined variable resistance and Since the adoption ci alternating current' energy supply and the development of increasing sensitivity in radio receivers in recent years, the) necessity has arisen for carefully shielding, from the varying currents or potentials which supply the energy to the receiver, all parts oi the receiver which carry the signal current to be amplified into the nal output oi theloud speaker.

The present invention is concerned, among other things, with the provision of a simple, practical and eilective shield between the supply switch and the variable resistance employed to control volume and citen associatcciwith the input grid or the amplifier tubes. Such a switch and resistance are commonly disposed in closely adjacent relation and are frequently interlocked so that when the volume control is turned up the switch will be automatically closed whereas when the volume control is turned all the way down the switch is thrown to open position. These conditions, coupled with the fact that the new types of vacuum tubes have a much greater amplification than those previously used and consequently render the receivers much more highly sensitive, makes it desirable to provide some simple and effective means for electrostatically and electrcmagnetically shielding the variable resistance of a volume control from the power supply switch.

One of the principal objects of the present invention is to provide for such a shield and to so constitute and combine the structure that the shielding is had while furthering compactness and simplicity of construction and general operating emciency.

Another object is to provide for complete shielding, both electrostatic and electromagnetic, irrespective of the number of terminals employed in and associated with the resistance and switch and even though a relatively large number of live parts may be juxtaposed to the variable resistance or vice versa.

Another object is to provide for the shielding in all positions oi the parts.

A further object is to provide an improved type oi adjustable resistance and one which is so compactly organized that it may be conveniently used in crowded quarters.

A still further object is to provide an improved and simplifiedl means for holding the resistor and terminals of the variable resistance in place; and to improve the adjustable contact thereof and the manner of mounting, biasing and adjusting the same as Well as the means employed for conveying current thereto.

Other objects and advantages reside in ce1- tain novel features of the construction, arrangement and combination of parte which will be hereinafter more iully describedand particularly pointed out in the appended claims, reference being had to the accompanying drawings, forming a part of this specification, and in which:

Figure 1 is a view in section taken on line i-I of Figure 2, illustrating one embodiment of the invention, and parts being shown in elevation for the sake of illustration;

Figure 2 ls a view in transverse vertical section taken on line 2-2 oi Figure l;

Figure 3 is a view in elevation showing a cover and switch, the cover being removed from the housing of the adjustable resistance;

Figure 4 is a fragmentary sectional view taken on line ll-i of Figure 3;

Figure `5 is a perspective view ci the large shielding disc;

Figure 6 is s view in longitudinal cross section taken on line @-t of Figure 'I and showing another embodiment of the invention;

Figure 6* is a detail view taken on line a--a of Figure 8;

Figure 7 is a view in transverse section taken on line --l of Figure 6;

Figure 8 is a view in elevation looking toward the left in Figure 6, but showing the device as it appears with the metal housing cup and parts of the variable resistance carried thereby removed';

Figure 9 is a group view in perspective illustrating the resistor, its split clamping ring and the tapered terminal and ring employed for maintaining the .parts assembled;

Figure l0 is a view similar to Figure 6 but showing still another embodiment oi the invention;

Figure l1 is a view taken on line ii-II of Figure 10:

'the invention.

shown in Figures 10- andV l1;

Figure i3 is a detail perspective view illustrating the additional shield employed in this formm of the invention; Figure 1d is a detail sectional view taken on line itl-id of Figure il; and

Figure l5 is a fragmentary view similar to Figure l0 but showing. another modied form of Referring to the drawings, and more particularly to Figures 1 to 5, it will be seen that the invention, in one embodiment, comprises a housing i which may be molded of suitable material such as Bakelite or hard rubber. A resistor 2 is provided and lconsists of a flexible backing strip usually of insulating material to one face of which a resistive coating of graphite or the like is applied. The resistor 2 is held-atly against the end wall 3 ofthe housing by means of rivets 8 which also electrically connect the ends of the resistor 2 with terminals 5. An arcuate contact strip 6 overlies the resistor 2 and has an angular extent of approximately three-quarters of a circle. 'I'he spaced ends of the arcuate strip 8 have integral therewith inwardly extending radial arms 1 which merge into a central yoke-like hub 8. A third outwardly extending intermediate arm 9 is also integral with the hub 8 and at its outer y end is secured to the housing and electrically connected to a third terminal II by means of a rivet I0. The yoked hub 8 straddles an operating shaft Il but is electrically insulated therefrom by means ofi insulating washers 8'. A

- metallic spring washer 8B coacts with insulating washer 8' to maintain the yoked hub 8 properly positioned axially of shaft I1. The contact strip 6 is thus so mounted that the inherent resiliency of the metal of which. it is composed tends to maintain it out of contact with the resistor. However, any portion of the strip may be pressed into contact iwith the resistor by rotating a metallic disc-like structure I2 which carries a pressure pad or button I3, the latter bearing against the strip 6, and serving to displace the portion of the strip 8 against which it bears into engagement with the resistor 2. 'I'he disc I2 may be slotted as at I4 to accommodate a stop I5 -which limits the movement of the disc in either direction. The center of the disc I2 is apertured the stop i5 may be kutilized for this purpose. At one end the stop l 5 may be provided with an apertured angular extension 22 which may be clamped against the housing i by the nut i9. The other end of the stop i5 may be extended through a slot 28 provided in the cap 2i and then bent over as at 2d to hold the cap assembled with the housing.

, The cap 2i may have an oset portion 25 apertured to accommodate an insulating casing or panel 2d for a switch designated generally at S, the switch casing 2S being suitably riveted as at 2l to the cap or cover.v The switch is shown as a snap action toggle type switch, and comprises a movable contact 2d constituting an arm of a toggle and selectively engageable with and disengageable from a ixed contact 3d. The movable contact 2t and fixed contact 3e are electrically .connected with suitable terminals provided on The the exterior of the insulating casing 26. other member of the toggle is designated at 3i and may be of molded insulating material. Both toggle members 28 and 3i are mounted on a common pivot 32 although axially spaced along ythe pivot by insulating washers 33. A spring 34 is provided and has one end pivotally connected with the arms 28 as indicated at 35 and its other end pivotally connected with the arm 3| as indicated at 3S. The spring is so tensioned and so interconnected with the arms ofthe toggle that itsl biasing action automatically changes or reverses as the toggle member 3| is swung to one side or the other, or, in other words, as the pivotal connection 38 is swung to one side or the other of a line extending through pivot axis 32 and the other pivotal spring connection 35. As illustrated, the toggle member 3l is of U-shaped cross u section and is positioned so that a roller-like prothe direction in which I1 will, in certain adjustments jection 37 constrained to rotate with the shaft wipe between the side flanges toggle member 3l, thereby swinging the toggle member to one side or the other depending upon the projection 31 is moved and consequently effecting opening or closing operating shaft Il. The shaft Il'is supported for rotation in a bushing I8 -which has a flanged end fastened to the wall 3 of the housing-by means of a nut I9. This `bushing may be employed to support the unit on the mounting panel or chassis of the receiver in the ordinary way. A suitable operating knob 20 may be pinned or otherwise secured to the other end of the shaft I1.

In the construction as thus far described rotation ci the knob 20 and consequent rotation of its shaft I1 and the disc I2 will vary the point at which the arcuate strip 5 engages the resistor and hence vary the value of the resistance in the circuit. It will be understood that current will flow from either terminal 5.through the portion of the resistor included in the circuitand from the resistor through strip 6, arms 1 and 8 and rivet I0 to the terminal II.

A metallic cap or cover 2l is provided for the open end of the housing and may be appropriatelysecured in' place. As shown in the drawings.

of the switch. The parts are so arranged that when the volume control is turned up a little the switch is turned to closed position, whereas when it is turneddown as far as it may be the switch will be moved to open position.

'I'he present invention proposes to provide an eil'ective shield between the switch S and the adjustable resistance in all positions of theseparts. To some extent. shielding is had by virtue of the presence of the Vmetallic disc-like structure I2, which, being connected to the shaft I1, is thereby grounded. It has been many years to mount bushingssuch as I8 on the chassis of the receiver which is connected to ground. As a consequence, in an arrangement such as described, the rotatablemetallic disc or broad spring shoe I2 is at ground potential and being interposed to a large extent between the live parts of the switch and the variable resistance operates as an electrostatic and electromagnetic shield. However, there are some of the live parts of the switch not thoroughly shielded from the resistance by the part I2, as will be understood .by a consideration of the outline of the disc I2 of the resistance. 38 and 39 of the common practice for also secures disc I2 to the shaft. The disc 40 is provided with a circumferentially extending slot 42 to accommodate the stop I5 and may also be used to carry the projection 31. The shield 40 turns with the shaft and is effective in all positions to electrostatically and electromagnetically y is contained in the housing, designated generally p at H, made up in part of a shallow metal cup 45, to the inner face of the body of which a at disc 45 of insulating material is secured. The insulating disc 48 may be secured in place by the upset inner end 41 of a mounting bushing 4l which is in this way also connected to the apertured central portion of the body of the cup 45. The housing for the resistance also includes an annular body member 49 of insulating material, a portion of which telescopes into the metal cup 45. A resistor 50 is provided and may comprise a flexible strip -having a resistive coating applied to its inner surface. The strip 50 is positioned against the inner wall of the annularhousing member 49 and is secured in position by means of a split expansible clamping ring 5| which may be made of fiber or other insulating material of appropriate elasticity or resiliency and which has one of its side faces positioned against the inner side of an lnturned annular flange 49h integral with one end of the body member 49.

A ber key 50' is tightly driven into a key-way provided therefor in the housing member 49 and engages between the ends of the resistor 50 and also between the ends of the split clamping ring 5| to locate these parts properly in the housing 49.

Terminals 52 and 52' are electrically connected with the ends of the resistor 50 and project exteriorly of the resistance housing H. The terminals 52 and 52' are of identical construction and, as shown in Figure 6", each has an langular portion 52'* accommodated in an opening 49a provided in flangeA 49b and also in a groove 49P formed in the-inner side face of said flange 49h, the annular portion 52'L of each of the terminals having an appropriately shaped extremity 52b snugly engaging the adjacent portion of the resistor 50.

The outer periphery of the ring 5I adjacent the split is notched as at 5I to accommodate the inner extremities 52* of the terminals 52 and 52' so that the ring 5I, when expanded, not only holds the resistor 50 but also the terminals 52 and 52' in place. Suitable means is provided for expanding the ring 5I so that its periphery clamps the resistor 50 against the inner wall of the annular housing member 49 and the terminals 52 and 52 against the resistor. In the present instances` it is proposed to utilize a third terminal 54 for this purpose and, to adapt the terminal to perform this function, it is tapered, as clearly shown in Figure 9. In the assembly, the tapered portion of the terminal 54 engages in notches 55' and 55 formed in the end 55 of the ring and a shoulder 56 presented by a wall of the notch on the inner periphery of the other end'of the ring. Thus.

l the tapered terminal 54, by forcing the ends of the split ring away from each other at the split, brings about the desired expansion and clamping of the resistor and the other two terminals. The

terminal 54 may beformed integral with a conducting ring' 51 which is disposed against the inner side face of the split ring 5i.

The movable contact of the variable resistance is designated at 52 and is in the form oi a roller or short cylinder having rounded ends, the periphery of the roller contact bearing directly against the resistive coating of the resistor 50. The contact 62 is urged into engagement with the resistor 50 by means of a spring ring 58 which also serves a current collecting and conveying ring.

The ring 58 is of special construction in that it is stamped or cut out of a fiat sheet of metal to the outline shown and hence the resilient or spring action of all such rings 58 on their movable contacts 52 is uniform. Uniformity of action in this particular ls of special importance in ance.

plying the requisite outward pressur variable resistances of this character. As shown in the drawings, the ring 58 is in the form of a split circular strip and has one end deflected laterally from the plane of the strip to provide a collecting shoe 59 which wipes against the conducting ring 51 and insures passage of electric current from the conducting ring 51 to the movable contact 62 in all adjustments of the resist- The opposite end of the ring 58 is enlarged as at 80 and notched as at 6I, the notch 5l receiving or straddling a portion of the contact 62 so that the tension or spring of the ring 58 is properly applied to the contact 62 whereby the contact 82 is urged withv proper pressure against the resistor 50.

The ring 58, except for its collecting shoe portion 59, is disposed flatly against one face of a carrier disc 63 of insulating material and is connected to the disc to rotate therewith by means of a tongue integral with an intermediate portion of the ring and extended through a slot 56 in the disc and then clenched or bent into firm engagement with the back of the disc. The disc 63 generally is of circular form except that one portion of its periphery is slightly enlarged and provided with a notch 61 which also receives a portion of .the roller contact 52, the arrangement being such that the walls of the notch61 of the carrier disc 63 perform the function of transmitting angular movement or adjustment to the movable contact 62 and ordinarily leaves to the spring strip or ring 58 merely the duty of ape to the contact 52 and of conveying current thereto from the terminal 54 and conducting ring 51.

'I'he disc 53 has a non-circular opening in its center which is snugly fitted on a correspondingly formed inner end portion 6,4 oi' an operating shaft 54 supported for rotative movement in the bushing 48 and constrained against any axial movement by the provision of a shoulder 64a on the shaft engaging one end of the bushing 48 and yby the assembly held on the inner end of the shaft by its upset end 54". This assembly includes the carrier disc 63, just described, an appropriate spring washer 48il and a conical cupshaped shield 90, which will be hereinafter more fully described.

With the construction as thus far described, current flows through terminal 54 and conducting ring 51 to the shoe 59 at one end of the ring 51 and thence through the ring 51 to the roller contact 52. From the roller contact 62 the curl rent flows through the resistor 50 to the terminals 52 and 52'. The amount of resistance incorporated in the circuit depends upon the anguiar position of the contact 62 with respect to 4at 13 to secure the parts assembled. 'I'he switch 'l0 has terminals 14 and 15 fastened to the housing 1| by rivets 16 and 11. The inner head of the rivet is rounded ofl as at 18 to provide one contact of the switch. The rivet 16 secures aasaiaa double pole single throw, a single pole double throw, or a so-called four-point switch. Other switch combinations may be had with suitable variations in the switch structure. The present invention, however, is concerned primarily with shielding the resistance in a combination of in position the other contact 19 of the switch which is in the form of a spring and has a portion 80 offset or spa'ced from as well as opposed to the contact 18. These contacts 18 and 19 may be electrically connected by a bridging contact 8| in the form of a double headed rivet which is carried by a piecey of insulating material 82 constituting one arm of a toggle. The toggle arm 82 is pivotally mounted on a pivot pin 83 supported by the switch housing 1| and serving also as the pivotal axis of a second toggle arm 84 which is shorter than the arm 82 and overlies the same. A spring 85 is provided andvhas its intermediate portions coiled and its ends interconnected with the arms 82 and 84, the spring being so related to the arms that it is eiective to bias the arm 82 and consequently its bridging contact 8| either to switch opening or switch closing position depending upon the adjustment of arm 84. The arm 84 is provided with spaced flanges 86 and 81 which project toward the adjustable resistance and which are adapted to be engaged by an operating projection 88 rotatable with a movable portion of the resistance so that as the resistance is turned up the switch will be thrown to on position and yet when the resistance is turned down as far as it may be the switch is turned to its off positionpall in a manner very similarto that described more at length in connection with the previous embodiment of the invention.

In the present construction the projection 88 is shown asbeing integral with the metallic cuplike shield 90 which is securely fastened to the operating shaft 64 and which effectively interposes an electrostatic and electromagnetic shield between the switch and the adjustable resistance.

The shielding cap is at ground potential, this being effected in the construction shown by virtue of its direct connection to the metal shaft 64 which is in turn grounded through the bushing 48 on the chassis of the receiver. By so combining the shield 90 withthe shaft 94 and so interposing it between the resistance and switch, it is eiective at all times and in all adjustments and yet the device is very compact and the resistance and switch operatively interlocked.

. In the form of the invention shown in Figures 10 to 13, inclusive, the adjustable resistance of the device is substantially the same as -that shown in Figures 6 to 9, inclusive, and the parts thereof are correspondingly numbered, and the foregoing description appliesthereto. In Figures 10 to 13 a different type of switch is shown and is such as to necessitate additional shielding over that afforded by the shielding cup 90. -In general, the switch arrangement provided in Figures 10 to 13 is such that there is available a this sort where the switch arrangement is such as to involve quite a multiplicity of terminals and consequently a more or less aggravated shielding problem.

In the construction shown in Figures 10 and 13, a washer 95 of insulating material is interposed between the outer open end of the housing 49 and the terminals of the adjustable resistance carried thereby and a shallow metallic cup-like member 96. 'I'he switch associated with the resistance is carried by but electrically insulated from this cup-like member 96 which serves both as a carrier and as a shield. To the inner surface of the body of the member 98 an insulating washer 91 is applied. A circular switch panel 98 of insulating material is held against the outer end of the member 96 by means of bent-over extensions 99 oi the metallic cuplike member 45. i 'I'he switch is provided with terminals |00, |0|, |02 and |03, all mounted on the insulating panel 96. The terminals |00 and |02 are connected to spring contacts |04 and |05 which are oilset inwardly from the inner face of the panel 98 and overlying a toggle plate |06 of insulating material. The terminals |0| and |08 are integral with the contact strips |01 and |08 which underlie the insulating toggle plate |06. In one position of the toggle plate, strip |01 is electrically connected to strip |06 and strip |08 is electrically connected to strip |04 by means of bridging contacts |09 and ||I, carried by and extending through the toggle plate |08. In Figure 11 these contacts |09 and ||0 are shown in the open position of the switch but when the toggle plate is swung in a clockwise direction as viewed in Figure 11 to the closed position of the switch, the contact ||0 has its underside still riding on the strip |03 and has its upper surface engaged with the contact |04. Similarly, at such time the contact |09 is engaged with the strips |01 and |05 and electrically connects them.

The toggle includes a second arm sup'- ported for pivotal movement on the same pli/0|; pin ||2 that serves as the axis of rotation of the toggle plate |06. A toggle spring ||3 interconnects the toggle arm and biases the switch to open vor closed position depending upon the position to which the arm is swung. This arm i has anges M4 and H5 cooperable with a projection 6 integrally formed with the shielding cup and functioning to interlock the resistance and the switch as in the other embodiments of the invention.

`.a stop finger |61 may be formed on the toggle arm and is cooperable with xed stop lugs H8 provided on a stop plate |09 to limit the movement of the toggle arm 9H in either direction. The stop plate H9 is' also mounted on thev tracting from the compactness of the structure nor its operative efiiciency.

It will be noted that the terminals of the reconstructions readily lend themselves to the use of so-called tap terminals similar to the terminals 52 and 52 and which may be clamped up against the resistor by the split ring at desired points intermediate the ends of the resistor.

The form of the invention shown in Figure 15 is identical with that shown in Figure except that the metallic cup-like shield 06 is omitted and in lieu thereof an auxiliary metal shield |30 is provided. The shield |30 is in the form of a flanged cup which has its body portion |3| suitably secured to the shield 30 as for example by metal tongues |32 struck from the shield 30 and extended through openings in the shield |30 and clamped thereagainst. The flange |33 of the shield |30 extends outwardly in a spaced or annular groove |34 provided therefor in the molded housing |35 which replaces the switch housing shown in Figure 10. Thus, the shield |30 and its flange provides a complete shield or barrier between the terminals of the switch and the terminals of the rheostat or resistance. The shield |30 is grounded through the shaft il as before. The terminals of the adjustable resistance may bgcovered by an annular insulating disc |36 which is clamped in position by the sections of the housing.

While I have shown and described typical constructions in which the invention may be advantageously embodied, it is to be understood that these several constructions have been selected merely for the purposes of illustration or example and that various changes in the size, shape and arrangement of the parts may be made without departing from the spirit of the invention or the scope 'of the subjoined claims.

The inventibn claimed is:

1. An electrical control device comprising a housing, a variable resistance therein, a switch carried by said housing in close proximity to the resistance, a common operating shaft for said variable resistance and said switch, said operating shaft being grounded, and an electric shield comprising an electrically conductive metal disc fixed to and electrically connected with the shaft and interposed between the live parts of the switch and the variable resistance to completely shield the resistance.

2. An electrical control device comprising a sectional housing, a variable resistance in one section of the housing, a switch in another secltion of the housing, a common operating shaft for the resistance and switch, said operating shaft being grounded and a conductive disc fixed to and electrically connected with the shaft and disposedl within the housing in between the switch and resistance whereby to provide' an electric shield for the resistance. v

3. A-control device comprising a housing including a plurality of sections, a variable resistance device disposed in one of said sections, a switch disposed in another of said sections, a grounded conductive electric shield interposed between said variable resistance and said switch, means for securing said housing sections together, and an actuator positioned in one of said sections for operating said variable resistance device and switch and also serving to support said shield.

4. An electrical control device comprising a housing, a variable resistance therein, a switch carried by said housing in close proximity to said resistance, a common operating element for said variable resistance and said switch, and a conductive electrical shield between said switch and said variable resistance and mounted on and electrically connected with said operating element, said operating element being at ground potential.

5. An electrical control device comprising a sectional housing, a variable resistance in one section of the housing, a switch in another section of the housing, the terminals of the resistance extending outwardly between the housing sections, means for securing the housing sections assembled, a common operating shaft for the resistance and switch, said operating shaft being at ground potential, and a conductive disc fixed to and electrically connected with the shaft and disposed within the housing in between the switch and the resistance whereby to provide an electric shield for the resistance.

6. An electrical control device comprising a sectional housing, a variable resistance in one section of the housing, a switch in another section of the housing, a. common operating shaft for the resistance and switch, said operating shaft being at ground potential, and a conductive disc in the form of a shallow conical cup fixed to and electrically connected with the shaft and disposed within the housing in between the switch and the resistance whereby to provide an electric shield for the resistance.

'7. An electrical control device comprising a sectional housing of insulating material, a variable resistance in one section of said housing and having its terminals extending outwardly between the housing sections, means for securing the housing sections assembled, a switch in another section of the housing, a metallic shield interposed between the section housing the switch and the section housing the resistance and insulated from the terminals of the resistance, said shield being at ground potential, a

. common operating shaft for the resistance and switch, said operating shaft being grounded, and a conductive shield fixed to and electrically connected with the shaft and disposed within the housing between the switch and the resistance.

8. An electrical control device comprising a sectional housing, a variable resistance in one section of the housing and having its terminals extending outwardly between and insulated from the housing sections, means for securing the housing sections assembled, a switch kin another section of the housing, a cup-like metallic shield embracing one ofthe housing sections and having a porticn interposed therebetween and insulated from the terminals of the resistance, said switch also having a plurality of terminals and said shield serving to electrostatically and electromagnetlcally shield the terminals of the resistance from the terminals of the switch, a common operating shaft for the switch and resistance, said operating shaft being grounded, and a metallic disc fixed to and electrically connected with the shaft and disposed within the housing between the switch and the resistance, said cup-like shield being electrically connected with said shaft.

9; A variable resistance and power switch unit of the character described comprising a housing having walls closing the ends thereof, a resistance element supported within the said housing adjacent one of said end walls, switch mecha nism mounted within said housing adjacent the other end wall, a metallic bushing interconnected with one of said end walls and having a portion disposed exteriorly of the housingi a metallic edective resistance of said element and means on said disk to actuanteA said switch mechanism. 1li. A variable resistance and power switch of the housing, a metallic disk directly xed to said the character described comprising a housing. a

resistance element disposed within the housing. switch mechanism disposed within the housing in close proximity tothe resistance, a grounded shaft supported for rotation and extending into shaft within said housing and interposed between and electrically insulated from the resistance element and the switch mechanism, means actuated by the shaft to vary the effective resistance of said element and means on said disk to actuate said switch mechanism.

ERWIN R. STOEKLE. 

